The present invention relates to a gravure printing press having a crowbar circuit that reduces the voltage and electrostatic charge applied to the press upon the detection of a fault condition.
Gravure presses are conventional printing presses in which a relatively large voltage is applied to the press to enhance the quality of the printing. A gravure printing press is described in U.S. Pat. No. 3,477,369 to Adamson, et al. The use of a large voltage in a printing environment presents a danger due to the presence of very small ink particles in the printing environment. Under certain conditions, the voltage could ignite the ink particles, causing an explosion.
To reduce the likelihood of such an explosion, a gravure press is typically provided with a crowbar circuit that removes the large voltage and the electrostatic charge produced thereby from the gravure press upon the detection of a fault condition. The crowbar circuit is typically activated for a relatively short period of time to remove the voltage applied to the press and to eliminate the electrostatic charge on the press. However, since the crowbar circuit is only activated for a short period of time, substantially all of the electrostatic charge may not be removed. As a result, the danger of explosion may still exist even after the activation of the crowbar circuit.